Restoring stream physical heterogeneity: effects on benthic macroinvertebrates Francesca Pilotto, Lina E. Polvi, Brendan Mckie, Christer Nilsson SFS, 22 nd May 2016

2 Physical heterogeneity  biota Application to stream restoration? Introduction – Study area – RQ – Methods – Results – Conclusions

3 Lack of biotic responses to stream restoration Occurrence of other stressors Poor recolonization potential Insufficient restoration measures Inadequate assessments  Planning of new restoration projects and management of restored streams Introduction – Study area – RQ – Methods – Results – Conclusions Physical heterogeneity  biota

Study area: Vindel river catchment Vindel river Sweden Umeå Stockholm Sweden Free-flowing river Length: 450 km Catchment area: 12,654 km 2 Glacial legacy sediments Forested catchment Introduction – Study area – RQ – Methods – Results – Conclusions

Channelization for timber floating Introduction – Study area – RQ – Methods – Results – Conclusions

Rågobäcken – basic restoration (2000s) Basic restoration Introduction – Study area – RQ – Methods – Results – Conclusions

Enhanced restoration (year 2010) Introduction – Study area – RQ – Methods – Results – Conclusions

PC1 (29%) Data from Polvi et al. 2014, Geomorphology Physical complexity Introduction – Study area – RQ – Methods – Results – Conclusions 29 metrics: sediment distribution, longitudinal profile, cross section, planform, instream wood

Research question: Do macroinvertebrate communities respond to increased physical complexity after enhanced stream restoration? Introduction – Study area – RQ – Methods – Results – Conclusions

time Enhanced restoration Methods - Streams with paired reaches with basic (n=4) and enhanced (n=4) restoration - Additional channelized and un-channelized reaches - 4 sampling occasions Introduction – Study area – RQ – Methods – Results – Conclusions

B: basic restoration, E: enhanced restoration, Mean ± S.E., pairwise comparison: n.s. Introduction – Study area – RQ – Methods – Results – Conclusions Taxonomic diversity BeforeAfter

B: basic restoration, E: enhanced restoration, Mean ± S.E., pairwise comparison: *=p ≤ 0.05 Introduction – Study area – RQ – Methods – Results – Conclusions Taxonomic composition

Dispersal traits B: basic restoration, E: enhanced restoration, Mean ± S.E., pairwise comparison: *=p ≤ 0.05 Introduction – Study area – RQ – Methods – Results – Conclusions

Correlation with gradient of physical complexity:

EPT %n.s * Diptera %n.s * Bivalvia %n.s * Xylophages %n.s * Filter feeders %n.s.+0.79*+0.77* Scrapers %n.s * Fast flows %n.s * Aquatic passive %n.s. n.s.(+0.51) Introduction – Study area – RQ – Methods – Results – Conclusions Taxonomic composition Functional composition Correlation with gradient of physical complexity: Pearson´s correlation coefficient, *=p ≤ 0.05

EPT %n.s * Diptera %n.s * Bivalvia %n.s * Xylophages %n.s * Filter feeders %n.s.+0.79*+0.77* Scrapers %n.s * Fast flows %n.s * Aquatic passive %n.s. n.s.(+0.51) Introduction – Study area – RQ – Methods – Results – Conclusions Taxonomic composition Functional composition Correlation with gradient of physical complexity: Pearson´s correlation coefficient, *=p ≤ 0.05

EPT %n.s * Diptera %n.s * Bivalvia %n.s * Xylophages %n.s * Filter feeders %n.s.+0.79*+0.77* Scrapers %n.s * Fast flows %n.s * Aquatic passive %n.s. n.s.(+0.51) Taxonomic composition Functional composition Introduction – Study area – RQ – Methods – Results – Conclusions Correlation with gradient of physical complexity: Pearson´s correlation coefficient, *=p ≤ 0.05

Introduction – Study area – RQ – Methods – Results – Conclusions Conclusions Benthic macroinvertebrates did respond to increased channel physical complexity Taxonomic and functional composition Responses appeared 5 years after restoration Landscape-scale approach Long-term monitoring

BioRest: Local- and landscape-scale effects on biodiversity after stream restoration Acknowledgments Collaborators: Lena Kretz, Cloé Lucas, Jelmer Van Doorn Department of Ecology and Environmental Science Umeå University Umeå, Sweden